A man salvages his belongings from the rubble of a damaged shop after Cyclone Amphan made its landfall, in South 24 Parganas district in the eastern state of West Bengal, India, on May 21, 2020. Image: REUTERS

The point will come, as with most of the other climate changes, when the local environment is no longer compatible with a normal human lifestyle.

I’ve never really believed the story climate crusaders tell to explain why so many people don’t get the message. You know, the one where if you drop a frog into a pot of boiling water it will hop right out, whereas if you just turn the heat up slowly it won’t notice. It will stay there and boil to death.

I’ve never actually tried the experiment, but surely not even frogs are that stupid. And I’m pretty sure human beings aren’t.

So why didn’t the good people of Houston start campaigning against global heating after Hurricane Harvey in 2017 left a third of their city underwater?

Why didn’t the citizens of the Philippines demand that their country end its heavy reliance on burning coal for power after Typhoon Haiyan killed at least 6,300 of them in 2013?

Why weren’t the survivors in the state of Orissa up in arms about India’s greenhouse gas emissions after the most intense cyclone in history killed 15,000 of them in 1999?

Well, partly because there were no data proving that the warming was making the tropical storms worse. Pretty well everybody in the meteorological trade and a great many lay people assumed that to be the case, but the evidence just wasn’t there. Until now – and as if to celebrate its belated arrival, here comes another monster storm.

On Sunday and Monday Super-cyclone Amphan spun up quickly over the warm waters of the Bay of Bengal, goingfrom nothing much to a Category 5 tropical storm and adding 175kph to its sustained wind speed in only 36 hours. India’s meteorologists predicted that the surge of water when it hit the coast could be as high as3-5 metres.

Cyclones, typhoons and hurricanes (all the same phenomenon, just in different oceans) are capricious. Their winds drop rapidly over land, and they are most destructive if they move slowly and loiter just off the coast. But at best Amphan will be bad, and it could be very bad indeed.

At least a quarter of the world’s population is going to have to move in the next fifty years.Where to? No idea. With almost eight billion people, the world is pretty full up already.

People living around the Bay of Bengal know that the storms are getting worse: 140,000 people died when Cyclone Nargis struck the Irrawaddy Delta in Burma (Myanmar) in May 2008. So do people living around the Caribbean, on the US eastern seaboard, and at the western end of ‘typhoon alley’ (the Philippines, China, Korea and Japan).

But they needed hard evidence, and now they have it. A study by researchers at the National Oceanic and Atmospheric Administration and the University of Wisconsin at Madison, published on Monday in the Proceedings of the (US) National Academy of Sciences, confirms that there is a direct link between warmer oceans, more water vapour in the air, and bigger storms.

Not more storms, but MUCH bigger. In fact, the likelihood that any given tropical storm will grow into a Category 3 or higher hurricane (or the equivalent in terms of cyclones and typhoons) is rising by eight per cent per decade.

Could it just be natural variation? James Kossin, lead author of the new study, doesn’t think so: “We have high confidence that there is a human fingerprint on these changes.” The data extend over four decades, which means the number of Category 3+ hurricanes has grown by a third since 1980.

It can only get worse, as will almost every other climate impact. The average global temperature now is 1.1°C above the pre-industrial average, but there is already enough carbon dioxide in the air to give us another half degree C of warming when it delivers its final load.

Never mind all the extra carbon dioxide that will be dumped into the atmosphere next month, next year, next decade. What will just the amount that we have already put there do to the tropical storms? The point will come, as with most of the other climate changes, when the local environment is no longer compatible with a normal human lifestyle.

For the 500 million people who live around the Bay of Bengal, the world’s biggest bay, the breaking point may be massive cyclones and floods that are made worse by sea level rise. For others it may be intense heat and permanent drought. In some places, it will be famine. But at least a quarter of the world’s population is going to have to move in the next fifty years.

Where to? No idea. With almost eight billion people, the world is pretty full up already.

Interviewing a couple of climate scientists recently, I saw for the first time a graph, modelling the future of a runaway warming world, that explicitly included a ‘death’ term. Mass death, that is. It made me feel a bit frog-like.